It seems that everywhere you turn you are bombarded with carb-bashing rhetoric. Stores and food companies are even selling only low-carb products. The anti-carb craze has everything to do with the recent resurgence in high-protein fad diets. So what should we know about protein if we are concerned with losing or maintaining weight? How much do we need? What happens if we don't get enough or if we get too much? And what does all of this have to do with successful weight loss?

How Much Protein Do You Need?

When you don't get enough protein in your diet, all your organs are affected -- from the kidneys to the heart. The immune system also suffers greatly, so you are more likely to get sick and get infections.

So how much protein do you really need? Well, it depends on your sex, age, and weight:

Protein Recommendations for Men

19-30 years old

0.8 gram per kg per day (about 56 grams per day)

31-50 years old

0.8 gram per kg per day (about 56 grams per day)

51-70 years old

0.8 gram per kg per day (about 56 grams per day)

Protein Recommendations for Women

19-30 years old

0.8 gram per kg per day (about 46 grams per day)

31-50 years old

0.8 gram per kg per day (about 46 grams per day)

51-70 years old

0.8 gram per kg per day (about 46 grams per day)

SOURCE: the Dietary Reference Intakes report by the Institute of Medicine, 2002

NOTE: The popular low-carb, high-protein diets can contain about 145 grams of protein or more.

Dangers of Eating Too Much Protein

* High protein can mean high fat

If you are getting a lot of your protein (as part of a high-protein diet) from fatty animal foods, you are not only eating a high-protein diet; you are most likely eating a high-fat diet, too. And higher fat means more calories and an increased risk for weight gain. According to the Institute of Medicine's Dietary Reference Intakes report, saturated fat, trans fats, and cholesterol in food increases the "bad" LDL cholesterol and total cholesterol levels; therefore, this type of diet increases your heart disease risk. Certainly eating less saturated fat is universally accepted sage dietary advice. The quickest way to minimize your intake of saturated fat is to:

NOTE: The Atkins diet contains about 53% of total calories from fat and 20% from saturated fat alone.

*Higher protein means lower fiber

Fiber comes to us courtesy of plant foods, and plant foods are our main source of carbohydrates. So if you eat a very high-protein diet, chances are pretty good you are eating a lower-carb, lower-fiber diet, too. In its Dietary Reference Intakes report, the Institute of Medicine noted several adverse health effects associated with eating a lower-fiber diet:

constipation

increased risk of cancer

increased risk of obesity

increased risk of heart disease

increased risk of type 2 diabetes

Likewise, if you're eating a low-carb diet, you are also likely to be lacking important phytochemicals (that come from plant foods) and certain vitamins and minerals.

* Higher protein could mean low bone density

When your body breaks down the protein you eat, several types of acids are triggered. Your body neutralizes these acids with citrate and carbonate from the bone. Simply put, this means calcium loss increases as protein consumption increases. The Institute of Medicine's Dietary Reference Intakes suggests, although it is still considered to be controversial, that as you double the amount of protein in your diet, the amount of calcium lost through your urine increases by 50%. This not only increases the loss of bone calcium but also increases the risk of kidney stones by as much as 250%.

It doesn't matter whether you get your protein from animals or plants -- they have the same effect on calcium loss through urine, says Linda Massey, PhD, a researcher and calcium and protein expert with Washington State University in Spokane. But some plants, like grains and legumes (beans), have a little something going for them: They contain high amounts of potassium, and potassium helps decrease urinary calcium. Milk products can help lessen this effect, too. The high amounts of calcium in milk and milk products help compensate for the calcium that will be lost in the urine due to the digestion/absorption of the protein in milk.